In the formation of textile materials from extruded thermoplastic polymers, such as poly(alpha-olefin)s, application of a spin oil to the filaments, yarns, or other textile embodiments thereof, is a standard practice. Spin oil, also called spin finish, is an essential lubricating composition deposited on the surface of the man-made fiber to reduce the fiber-fiber friction and the friction developed as the yarn passes over the metal machinery surfaces. The primary function of a spin oil is to provide surface lubricity to the yarn. Spin oils also reduce the static charges in the hydrophobic fibers. They reduce the electrical resistance of the fibers thereby allowing faster dissipation of the charges. Spin oils help prevent fiber yarn breakage. Spin oil contains a large number of chemical components, the major components being lubricant, antistatic agent and emulsifier. In addition it can also contain small portions of additives such as antioxidant, corrosion inhibitors, defoamers and antibacterial product. The amount of spin oil needed depends on producer and on manufacturing steps which follow to convert fibers into useful end products. Typically between about 0.9% and 5% of spin oil is needed. A major disadvantage is that residues of spin oil on the extruded fiber reduce the soil resistance of the finished product.
In the industrial production of textiles, such as carpet and apparel, it is common to treat such substrates with a composition to impart added desirable properties thereto, such as resistance to soiling by particulate or dry soil. Certain fluorochemical compositions are commercially used for this purpose. They can be applied to various substrates by methods which include, for example, spraying, foaming, padding, and finish bath immersion.
U.S. Pat. No. 4,264,484 discloses a liquid carpet treating composition containing a water-insoluble addition polymer derived from polymerizable, ethylenically unsaturated monomer free of nonvinylic fluorine and having at least one major transition temperature higher than about 25.degree. C., and a water-insoluble fluoroaliphatic radical- and aliphatic chlorine-containing ester having at least one major transition temperature higher than about 25.degree. C.
U.S. Pat. No. 4,107,055 discloses a fabric coating composition, including a polymer having a glass transition temperature above room temperature, an ionic fluorinated surfactant and a carrier. The polymer is preferably applied to fabric at a rate giving a dry solids content of about 0.25 to 10%, to give dry soil resistance.
U.S. Pat. No. 4,043,964 discloses a coating which provides a durably soil-resistant carpet which contains (a) at least one phase of a specified water-insoluble addition polymer derived from a polymerizable ethylenically unsaturated monomer free of non-vinylic fluorine and (b) at least one phase of a specified water-insoluble fluorinated component containing a fluoroaliphatic radical of at least 3 carbon atoms. The monomer from which the fluorinated component is formed may contain dicarboxylic acid, glycol, diamine, hydroxyamine, etc.
A common feature of the treating or coating compositions disclosed in the above mentioned U.S. Pat. Nos. 4,264,484, 4,107,055 and 4,043,964 is that they are to be applied to the carpet or fabric after its production in a separate treating step. The application equipment and time required for such treating step add to the cost of the final product.
Textile fibers and yarns can also be treated by incorporation of the fluorochemical in the spin finishing bath. For example, U.S. Pat. Nos. 4,190,545 and 4,192,754 disclose spin finish and yarn finish compositions for incorporation with synthetic organic polymer yarn or yarn products to render the same oil repellent and resistant to soiling. The composition comprises (a) a solution of a salt of dioctylsulfosuccinate, propylene glycol and water, and (b) a fluorochemical compound consisting of polycarboxybenzene esterified with certain partially fluorinated alcohols and with hydroxyl-containing organic radicals such as 2-hydroxyethyl, glyceryl and chlorohydryl or bromohydryl.
Alternatively, treated textile fibers and yarns can be obtained by melt extrusion of a blend of a synthetic fiberforming polymer and a fluorochemical composition. Such melt extrusion is described for example in U.S. Pat. No. 3,839,312. This patent discloses that soil and stain repellency of extruded filaments of a synthetic resin can be improved by incorporating in the resin a small amount, about 1 percent, of an amphipathic compound having from one to four fluoroalkyl groups pendent from an organic radical. The repellency is provided by the fluoroalkyl groups, which tend to be concentrated at the surface of the fiber.
WO 92/18569 and WO 95/01396 disclose permanently soil resistant polymeric compositions such as fibers and yarns that have a fluorochemical dispersed throughout the polymer. These polymer compositions are prepared by melt extrusion of the fluorochemical with the desired polymer. Polymers that can be used with the fluorochemical include polyester, polypropylene, polyethylene and polyamide.
U.S. Pat. No. 5,025,052 discloses certain fluoroaliphatic group-containing oxazolidinone compositions. The patent also discloses fibers, films, and molded articles prepared, for example, by injection molding a blend or mixture of fiber-or film-forming synthetic organic polymers and certain fluorochemical oxazolidinones. The resulting fibers, films, and molded articles are said to have low surface energy, oil and water repellency, and anti-soiling properties.
European Pat. Pub. No. 0 516 271 discloses durably hydrophilic thermoplastic fibers comprising thermoplastic polymer and fluoroaliphatic group-containing non-ionic compounds.
While many currently used fluorochemical compositions have demonstrated utility in providing carpet with soil resistance, unfortunately a significant amount of the carpet manufactured cannot be treated to obtain the desired properties. The reason is that significant and varying amounts of spin oil often remain on the carpet face pile, lowering the soiling resistance of the carpet or acting as contaminants which interfere with the fluorochemical treatment and diminish or prevent the desired result thereof. Since in every carpet line different amounts of residual spin oil can be observed, it is difficult in the operation of a carpet mill to predict which of the carpet lines are going to present problems in obtaining satisfactory soil resistance. Scouring the carpet should be a solution of this problem. However, this method is not acceptable to the industry for economical reasons.
It is an object of the present invention to provide carpet yarn, more particular carpet yarn comprising a plurality of filaments of a thermoplastic polymer, that can overcome above mentioned shortcomings because of a reduced amount of spin oil needed to provide proper lubrication of the filaments, or, because as in one embodiment, the spin oil can be replaced by water. It is a further object of the invention to provide a method of producing a carpet yarn having improved soil resistance. Furthermore, it is an object of the invention to provide a process for converting the yarn into a carpet having high soil resistance.